Fluid actuated pump



y 31, 1966 R. P. VINCENT ETAL 3,253,549

FLUID ACTUATED PUMP Filed July 9, 1964 I L 4 n FIG.2

INVENTORS; RENIC P. VINCENT BY ARTHUR W. GARST FIGI ATTORNEY UnitedStates Patent 3,253,549 FLUID ACTUATED PUMP Renic P. Vincent and ArthurW. Garst, Tulsa, Okla., as-

signors to Pan American Petroleum Corporation, Tulsa, Ukltn, acorporation of Delaware Filed July 9, 1964, Ser. No. 381,348 5 Claims.(Cl. 103-44) This invention relates to pumping equipment of the typeoften used in lifting fluids from wells, and more particularly, itrelates to a fluid-actuated diaphragm pump for pumping corrosive fluidsfrom a well.

Various reciprocating pumps are available for pumping fluids, such asoil, Water or the like from wells, and a number of these pumps have beenfound satisfactory for handling most ordinary well fluids. However, thelifting of fluids liberated from underground oil-bearing formations bycombustion recovery methods presents problems for which there are nofeasible solutions at the present time. In some instances it has beennecessary to pull pumps employed in such service at twoor threedayintervals to repair eitherthe bottom hole pump or the tubing and suckerrod string because of damage resulting from the corrosive by-products ofcombustion. Corrosion and abrasion resulting from rod-on-tubing wear andwear of close fitting parts of the bottom hole pump accelerate metalloss on the parts and result in the early failure of the equipment.Needless to say, such maintenance is extremely expensive, and theresulting maintenance costs may, in some instances, render iteconomically infeasible to recover oil by this method.

An object of the present invention is a fluid-actuated diaphragm pumpespecially well suited for pumping corrosive or abrasive fluids.

Another object is such a pump wherein the pump fluids contacts a minimumnumber of moving parts in the pump.

Still another object is such a pump wherein the discharge tubing can becoated with a protective film Without the opportunity for mechanicalwear which tends to remove such coatings.

Yet, another object is such a pump having no tendency to gas lock.

A still further object is such a pump having increased diaphragm lifeduring service.

Still, a further object is such a pump wherein the correct amount ofpower fluid employed to actuate the diaphragm is maintained between thediaphragm and a reciprocating plunger.

These and other objects of the invention will become apparent byreference to the following description and accompanying drawing of apreferred embodiment of the invention.

In accordance with the present invention there is provided a pumpingdevice adapted to be connected into a string of well tubing and insertedinto a well. A cylinder containing a reciprocating plunger is connectedto a pump chamber having a flexible diaphragm, and power fluid, moved bythe reciprocating plunger, actuates the diaphragm to pump fluids fromthe well. A power oil reservoir is provided above the plunger and avalved port between the reservoir and the lower end of the cylinder isprovided to permit power fluid to be transferred Patented May 31, 1966to the reservoir when the pressure on the lower end of the plungerexceeds the fluid pressure in the reservoir. Also, means are provided topass power fluid from the reservoir to the space beyond the lower end ofthe plunger so the correct amount of power fluid is maintained on thepower side of the diaphragm to assure maximum pumping efliciency andprevent gas locking.

A pump of the same general type as that contemplated by the presentinvention is described in US. Patent 2,814,993. The pump of the presentinvention has been determined to be highly advantageous over such pumpsin that pumping efficiency is more easily maintained and the tendencyfor gas locking is reduced.

The present invention will be more fully understood by reference to thefollowing description of a preferred embodiment thereof, given'inconnection with the accompanying drawings wherein: 7

FIGURE 1 schematically illustrates a pumping device according to theinvention positioned in a well; and

FIGURE 2 illustrates a vertical cross-sectional view of a pump chamberand diaphragm employed in the device of FIGURE 1; and

FIGURE 3 is a sectional view of the chamber of FIG- URE 2, taken at line33.

Referring now to the drawings, wherein like numbers are employed in thevarious figures to designate like elements, a borehole 11 is formed inthe earth penetrating one or more fluid-producing formations. Wellcasing 12 maybe employed in the well, and the casing may be perforatedopposite the fluid-producing formation, or other suitable means may beprovided to admit the formation fluids 13 into the well. A string ofwell tubing 14 extends from the surface downwardly into the well, andcylinder 16 is connected to the lower end of tubing 14. This cylindermay be merely an extension of the tubing or may be a separate elementconnected to the tubing string. Reciprocating plunger 17 is positionedin cylinder 16 and is reciprocated therein by sucker rod string 18attached thereto and extending to the surface where it is attached to adrive mechanism (not shown) for reciprocating plunger 17.

Connected to the lower end of cylinder 16 is elongated, cylindrical pumpchamber 19 provided with inlet 21 below the level of fluid in the welland outlet 22. Outlet 22 communicates with discharge tubing 23 whichextends upwardly to the surface and conveys the pumped well fluids fromthe well. Lower standing valve 24 is provided in inlet 21 to permitunidirectional flow of well fluids into the interior of chamber 19, andupper standing valve 26 is provided in outlet 22 to permitunidirectional flow of fluids from the interior of chamber 19 todischarge tubing 23.

Positioned on the interior of chamber 19 is a diaphragm member, such asbladder 27 formed of a flexible, fluid impermeable material such asrubber, neoprene or other like materials compatible with the fluids tobe handled by the pump. Suitable reinforcing may be used in thediaphragm to secure the necessary. strength, and durability. Whilevarious configurations of diaphragms may be employed, such as a bellowsor flexible disc, an expansible and contractable bladder is preferred.The lower end of bladder 27 is connected in a fluid-tight manner toinlet 21 and the I upper end connected similarly to outlet 22 toeffectively divide chamber 19 into two variable volume compartments,i.e., a first compartment 20a inside the bladder and another compartment2% between the outside of the bladder and the interior wall of thechamber. The second compartment communicates with the lower end ofcylinder 16 beyond the end of the stroke of plunger 17 by way of conduit28 to supply a power fluid, such as a non-corrosive oil or othersuitable liquid to the second compartment.

Power fluid reservoir 29 is provided in the annular space between thesucker rod string 18 and tubing 14. Power fluid is maintained in thisreservoir to supply the power fluid to the outside of bladder 27. Tubing14 may be partially or completely filled with the power fluid. Powerfluid flow channel 31 is provided between the reservoir and the lowerend of cylinder 16 so that power fluid may flow from the reservoir intothe above-mentioned second compartment to keep it filled. Flow channel31 may be provided by a relatively small diameter orifice ex- I tendingthrough plunger 17, as shown, or a loose fit between the plunger and thecylinder wall may accomplish the same purpose. Ordinarily, only arelatively small amount of power fluid will be lost from the secondcompartment 20b, and a small orifice, for example, one having aninternal diameter of about /s inch, may be used. The cross-sectionalarea of flow channel 31 should be maintained as small as possible, sincepumping efficiency is adversely affected if too great a volume of powerfluid is permitted to pass from cylinder 16 to reservoir 29 during thedownward stroke of plunger 17.

A second, larger capacity flow channel, such as valved conduit 32 isprovided between reservoir 29 and compartment 20b. As shown, travellingvalve 33 is positioned in conduit 32 near the lower or working end ofplunger 17, and conduit 32 passes upwardly from the working end of theplunger to the power end, or upper end thereof. Valve 33 permitsunidirectional fluid flow from cylinder 16 into reservoir 29. Normallyvalve 33 is closed during both the up stroke and down stroke of plunger17. However, if too much power fluid is present in cylinder 16 andcompartment 20b, or if the fluid pressure in compartment 20b exceeds thefluid pressure at the working end of the plunger, then valve 33 opens topermit the transfer of power fluid from the lower end of plunger 17 tothe reservoir above the plunger.

Advantageously, the pressure of the power fluid at the top side ofplunger 17, i.e., at the lower end of reservoir 29 is greater than thehydrostatic head pressure of pumped fluid standing in discharge tube 23extending to the surface. This may be accomplished by employing as powerfluid a fluid of greater density than the formation fluid (where thevertical fluid columns are of equal height), by extending the height ofthe vertical power fluid reservoir to a level sufliciently greater thanthe elevation of the outlet end of the discharge tube, or by employing apressured gas cushion on top of the fluid in reservoir 29. For example,if the formation fluid is mostly water and the power fluid is an oil,tubing 14 may be filled with oil 36 from surge vessel 37 connected tothe upper end of the tubing, and a suitable gas 38, such as air ornitrogen, may be maintained under pressure in the vapor space above theoil in vessel 37 to achieve the desired pressure differential across thepump.

Advantageously, as shown in FIGURES 2 and 3, an internal support isprovided inside of bladder 27. This internal support 41 comprises anelongate cage formed of, for example, four vertical rods 42 equallyspaced around the perimeter of the bladder when in the expandedcondition. A central vertical rod 43 is connected to the outer rods 42by vertical plate members 44. The circumference of the expanded bladderis substantially the same as the internal dimension of chamber 19, andthe perimeter of support 41 is substantially the same as thecircumference of the expanded bladder. End pieces 4-6 are tapered towardthe middle in a conical shape. This configuration assures that therubber-like bladder does not stretch during operation of the pump, andonly flexing of the bladder occurs.

In the operation of the pump described above, power fluid is maintainedin tubing 14 at the desired pressure. As plunger 17 moves upwardly thepressure in cylinder 16 below the plunger, and consequently incompartment 20b, is reduced by the upwardly moving plunger reducing thepower fluid pressure below the plunger. Formation fluid pressure causesthe formation fluid to enter cornp-artment 20a through inlet 21 andexpands bladder 27 outwardly against the wall of chamber 19. When thedirection of movement of plunger 17 is reversed and the plunger beginsits downward movement and the full pressure of the column of power fluidin reservoir 29 is applied to the outside of bladder 27 to cause it tocontract and expel the formation fluid through outlet 22 and intodischarge 23 by which the pumped fluid is conveyed to the surface.During the travel of plunger 17 power fluid from the reservoir may passthrough flow channel 31 as needed, and if the pressure below the plungerexceeds that above it, valve 33 permits power fluid to move from thespace below the plunger to the reservoir as mentioned above.

A pump of the type described above has been constructed and operatedvery satisfactorily, with a volumetric efliciency very close to percentbeing achieved at a discharge pressure between 800 and 900 p.s.i.g.

From the foregoing description of a preferred embodiment of the presentinvention, various alterations and modifications in the constructionthereof may become apparent to those having ordinary skill in the art.It will be understood that such alterations and modifications fallwithin the spirit and scope of the invention as defined by the appendedclaims.

We claim:

1. A pump for pumping fluids from a well bore which comprises:

a first tubular member suspended within said well, and

a power fluid cylinder provided at the lower end of said tubular member;

a second tubular member suspended Within said well;

a string of sucker rods within said first tubular memher;

a plunger within said power fluid cylinder and connected to said stringof sucker rods;

conduit means in said plunger extending axially therethrough, saidconduit means having a valve therein permitting unidirectional flow frombeneath to above said plunger when the fluid beneath said plungerreaches a given pressure;

a pump chamber adapted to be connected to the lower end of said powerfluid cylinder;

a flexible diaphragm member in said pump chamber,

said diaphragm dividing said chamber into a first variable volumecompartment and a second variable volume compartment;

a valve inlet in communication wit-h said first compartment;

a valve outlet in communication with said first compartment fordischarging fluid therefrom, said valve outlet being fluidly connectedto said second tubular member;

second conduit means establishing fluid communication between saidsecond variable volume compartment and said power fluid cylinder belowsaid plunger.

2. An apparatus as described in claim 1 in which said plunger has anunobstructed flow channel axially extending therethrough.

3. An apparatus as described in claim 1 including a power fluid withinsaid first tubular member, said fluid being of sutficient head anddensity so as to have a greater hydrostatic head pressure than that ofthe fluid being pumped Within said second tubular member.

5 3 4. An apparatus as defined in claim 1 in which said References Citedby the Examiner diaphragm member comprises an expandable and col- UNITEDSTATES PATENTS lapsible cylindrical bladder and said apparatus furtherincluding an internal support Within said bladder, said in- 2 gi g E225;ternal support including equispaced rods spaced inside 5' 2676569 1/1953g zg said bladder around its permieter when in an expanded g 11/1960Zmman condition, a central rod, and plate members connecting saidcentral rod With each said rods. FOREIGN PATENTS 5. An apparatus asdescribed in claim 3 including a 6,657 1894 Great Britain surge vesselat the surface in fluid communication with 10 the upper end of saidfirst tubular member. ROBERT M. WALKER, Primary Examiner.

1. A PUMP FOR PUMPING FLUIDS FROM A WELL BORE WHICH COMPRISES: A FIRSTTUBULAR MEMBER SUSPENDED WITHIN SAID WELL, AND A POWER FLUID CYLINDERPROVIDED AT THE LOWER END OF SAID TUBULAR MEMBER; A SECOND TUBULARMEMBER SUSPENDED WITHIN SAID WELL; A STRING OF SUCKER RODS WITHIN SAIDFIRST TUBULAR MEMBER; A PLUNGER WITHIN SAID POWER FLUID CYLINDER ANDCONNECTED TO SAID STRING OF SUCKER RODS; CONDUIT MEANS IN SAID PLUNGEREXTENDING AXIALLY THERETHROUGH, SAID CONDUIT MEANS HAVING A VALVE THERINPERMITTING UNIDIRECTIONAL FLOW FROM BENEATH TO ABOVE SAID PLUNGER WHENTHE FLUID BENEATH SAID PLUNGER REACHES A GIVEN PRESSURE; A PUMP CHAMBERADAPTED TO BE CONNECTED TO THE LOWER END OF SAID POWER FLUID CYLINDER; AFLEXIBLE DIAPHRAGM MEMBER IN SAID PUMP CHAMBER, SAID DIAPHRAGM DIVIDINGSAID CHAMBER INTO A FIRST VARIABLE VOLUME COMPARTMENT AND A SECONDVARIABLE VOLUME COMPARTMENT; A VALVE INLET IN COMMUNICATION WITH SAIDFIRST COMPARTMENT; A VALVE OUTLET IN COMMUNICATION WITH SAID FIRSTCOMPARTMENT FOR DISCHARGING FLUID THEREFROM, SAID VALVE OUTLET BEINGFLUIDLY CONNECTED TO SAID SECOND TUBULAR MEMBER; SECOND CONDUIT MEANSESTABLISHING FLUID COMMUNICATION BETWEEN SAID SECOND VARIABLE VOLUMECOMPARTMENT AND SAID POWER FLUID CYLINDER BELOW SAID PLUNGER.